Ultrasonic Evaluation of the Impact Damage of Polymer Bonded Explosives

The damage properties of polymer bonded explosives under dynamic loading were studied by using ultrasonic evaluation. Explosive samples were damaged by a low-velocity gas gun at different impact velocities. Ultrasonic examination was carried out with a pulse through-transmission method. Spectra analyses were carried outby using fast Fourier transform. Characteristic ultrasonic parameters, including ultrasonic velocities, attenuation coefficients, spectra area and master frequency, were obtained. The correlation between the impact damage and ultrasonic parameters was analyzed. A damage coefficient D was defined by considering a combination of ultrasonic velocity and amplitude. The results show that ultrasonic parameters can be used to quantitatively assess the damage extent in impacted plastic bonded explosives.     

岩石动态损伤特性的实验研究

利用一级轻气炮技术,对２类岩石进行冲击损伤实验,并对软回收样品进行了超声波测试,得到岩石的动态损伤与冲击波速和超声波传播特性的关系．结果表明声波衰减系数可作为描述岩石动态损伤的主要参量．     

强冲击载荷下岩石损伤特性实验研究

通过在一级轻气炮驱动的平板碰撞实验台进行冲击损伤实验 ,对软回收样品进行超声波测试 ,研究了强冲击载荷下两种典型岩石损伤特性 .结果表明 ,岩石的动态损伤与冲击速度和超声波衰减系数α有关 ,后者较好地反映了岩石的损伤程度 ,可作为构造岩石损伤模型的主要参量     

路轨跳线爆炸焊接连接技术试验研究

目的　研究路轨跳线的连接问题 .方法　采用爆炸焊接法进行路轨跳线的连接 .结果　试验结果表明 ,采用高爆速炸药进行爆炸焊接质量是可靠的 .结论　采用爆炸焊接法进行路轨跳线的连接是可行的     

Deformation and Failure of Polymer Bonded Explosives

The deformation and failure of pressed polymer bonded explosives under different types of loads including tension, compression and low velocity impact are presented. Brazilian test is used to study the tensile properties. The microstructure of polymer bonded explosives and its evolution are studied by use of scanning electronic microscopy and polarized light microscopy. Polishing techniques have been developed to prepare samples for microscopic examination. The failure mechanisms of polymer bonded explosives under different loads are analyzed. The results show that interfacial debonding is the predominant failure mode in quasi-static tension, while extensive crystal fractures are induced in compression. With the increase of strain rate, more crystal fractures occur. Low velocity impact also induces extensive crystal fractures.     

Detecting Impact Damage in Carbon Fabric/epoxy-matrix Composites by Ultrasonic F-scan and Electrical Resistance Measurement

The status and the variation of electrical resistance of impacted carbon fiber/epoxy-matrix composites were studied by ultrasonic F-scan and electrical resistance measurement The experimental results shows that impact damage energy threshold value of carbon fabric/epoxy-matrix composites can determine by using ultrasonic F-scan. When the impact energy exceeds the threshold value, damage is generated in composites. Electrical resistance of impacted composites is changed owing to the contact of each carbon fi...     

有保护层的岩石冲击损伤实验研究

利用一级轻气炮，对有保护层和无保护层的砂岩、花岗岩和大理岩试件进行冲击实验，并对试件进行冲击压力测试和声波测试，利用试件端面产生的冲击压力波形分析保护层对冲击作用的影响，利用实验前后的声波速度变化情况衡量岩石试件的损伤度。实验结果表明，在其它实验条件基本一致时，有保护层的岩石试件所受的冲击压力比无保护层时降低了60％左右；波速降低率也明显减小，损伤度降低率在14．8％～48．2％之间。说明保护层能够对受冲击作用的岩石起到很好的保护作用。     

冲击荷载下岩石动态损伤演化研究

I型裂纹破坏为岩石材料在冲击荷载作用下的主要破坏方式.通过假设岩石材料宏观上是一个均匀连续体,而细观上其内部则包含了大量随机分布的微裂纹等损伤缺陷;研究了岩石材料在冲击荷载下裂纹的成核、发展以及内部损伤演化规律;借助于宏细观相结合的理论建立了表征岩石材料细观结构及其损伤演化过程中的某种特征参量与宏观力学参数之间的关系方程.     

压力管道破坏的静载实验研究

目的研究压力管道耐撞性. 方法通过足尺实验模拟实际工程环境下压力管道的破坏. 通过计算机对自动采集的试验数据进行分析和绘图. 结果和结论压力管道耐撞性静载实验研究为理论分析奠定了基础, 为输送高压流体介质管网的耐撞性评价和安全设计提供了可靠的分析方法和重要的技术参数.     

Structural Damage Law of Semiconductor Bridge Detonator under Impact and Overload Environment

Aiming to know the requirement of penetrating the munition semiconductor bridge detonator under the impact overload environment, the impact overload simulation device and the structural finite element software ANSYS/AUTODYN are used to study the variation of the axial dimension, charge and the chip gap of the semiconductor bridge detonator under the impact overload environment. The typical semiconductor bridge detonator is affected by the acceleration, and the strain increases with the increase ...     

冲击载荷下脆性岩板损伤断裂演化的实验模拟研究

在矿山运输系统中,井壁围岩冲击损伤破坏对经济和安全效益的影响是至关重要的,因为动态冲击载荷对井壁围岩和支护结构会产生严重的削弱破坏作用,室内研究表明,岩石样品如岩板在动态载荷的冲击作用下会失效。为研究在低速冲击载荷作用下,脆性岩石损伤断裂的演化过程,利用分离式霍普金森压杆（SHPB）装置中压缩气体发射球体子弹对脆性岩板进行变角度冲击损伤实验,岩板受到冲击后,边缘出现凹坑,表面裂纹从撞击凹坑直达岩板边缘,实验中样品的表面裂纹能有效代表试样内部的开裂状况,能有效反映冲击能量的耗散、破裂区面积与裂纹表面积随入射能量呈非线性增长趋势,同时与入射角度相关,但当破裂区面积急剧下降时,裂纹表面积反而急剧上升,表明裂纹的发生发展有明显的孕育期,在入射能量达到临界值前,主要表现为裂纹孕育增长,在达到临界值后,发生宏观断裂破坏,裂纹面积呈负增长,破裂区面积增大。实验结果分析表明在实际工程中,围岩和支护结构的抗冲击的最优化设计角度范围在15°～30°。     

钢筋混凝土安全壳受撞击局部破坏作用计算

针对钢筋混凝土安全壳在事故撞击下的动力计算问题,建立了贯穿破坏的弹塑性计算模型,该模型考虑了安全壳的主要结构要素:混凝土、横向钢筋、纵筋和钢衬套的作用机理以及各结构要素的多阶段变形和受力特点,推导并给出了安全壳抗局部撞击的计算方法。计算分析表明,纵向钢筋网的整体作用是提供膜力,可等效为一定厚度的薄钢板;纵向配筋率、配箍率和钢衬套厚度均影响结构的抗力和变形,其中配箍率的影响最为显著。     

空间目标非灾难性撞击毁伤模型研究

针对空间目标在动能杀伤飞行器（kinetic kill vehicle,KKV）非灾难性撞击下的毁伤模型进行研究。对弹目撞击想定进行分析,结合NASA撞击解体判据,着眼KKV小型化发展趋势,指出广义顺轨拦截能够有效避免目标灾难性解体,减轻撞击事件对空间环境的污染;对目标易损性进行分析,基于目标功能构型建立目标毁伤树模型,以密度等效原则建立目标多层板靶等效模型;以THOR方程预估射弹侵彻效能;从部件物理毁坏和功能衰减2方面建立目标毁伤概率模型;进行仿真案例分析。算例结果表明：非灾难性撞击足以有效毁伤目标。     

云爆效应的毁伤效能研究

通过对云爆效应毁伤机理的研究,以及云爆弹与杀爆弹的静止对比试验,提出了常规弹药研制与改进的一种新思路,即在各弹药系统中添加一种云爆型弹头,提高弹药系统的综合作战能力,以达到高效毁伤的目的.试验结果表明:云爆弹的毁伤威力比杀爆弹有大幅度的提高.     

钝感炸药与平板装药的分析研究

目的　介绍高钝感炸药与平板装药 .方法　对 DO-XX炸药的爆速和爆压进行计算 ,对平板装药的爆速进行测试 .结果　分析研究了炸药装药的安全特性 .结论　可以满足工程设计的要求 .     

层状岩石损伤本构关系的研究

对常见层状复合岩石的损伤结构与本构关系进行了研究,电镜微观研究表明了其微观结构与微孔隙特征, 导出各分层在不等围压、不同有效应力、不同参数及不同损伤演化过程下的三维非线性损伤本构方程与演化方程,并得到实验的较好验证.     

Experimental Investigation on Shock Wave Characteristics of Aluminized Explosives in Air Blast

To investigate the shock wave characteristics of RDX-based aluminized explosives, air blast tests were conducted for measuring the parameters of 10.kg aluminized explosives which contained 0-40% aluminum. The results showed that with the increasing of aluminum content, the overpressures and impulses increase at first and then decrease within 7 m or 5 m, which reached the maximum when aluminum content was 20% or 30%. Power exponential formulas are used to fit the shock wave parameters vs scaled distance, where an equal weight of TNT is used to calculate the scaled distance. The overpressures of HL0 and TNT in tested locations not only conform to the similar law, but also conform to the same attenuation law after gaining the scaled distances of equal TNT mass. The pre-exponential factors of overpressure and impulse, k_p and k_I, decrease along with the increasing of Al content and keep the same pace as the calculated P_CJ. The attenuation coefficients a_P and a_I increase at first and decrease later with the increasing of aluminum content, and they reached the maximal values with 30% Al containing, which keeps the same pace as the calculated Q_V.     

岩体损伤与破坏过程研究

对层状岩体进行了损伤演化与破坏过程的研究,引入损伤变量及损伤扩展系数,建立符合岩体整个损伤演化过程的方程;描述了岩石在受载过程中初期近似呈线性,随后加速的过程;分析了层状岩体的损伤演化与破坏特征及其稳定性,解释了岩石损伤演化的规律。研究表明:层状岩体的损伤萌生与扩展直到破坏,除与加载大小、速率等因素有关外,还与各亚层损伤演化规律、载荷与层面夹角、各亚层的内部微结构特性等有关。     

金属材料疲劳损伤的激光与超声检测

用激光衍射谱谱面光强比Ｋ和超声速Ｃ的变化定义损伤变量Ｄ（Ｋ）和Ｄ（Ｃ），对ＬＤＳ和４０ＣｒＮｉＭｏＡ材料进行了疲劳损伤检测．结果表明：Ｋ和Ｃ的变化对疲劳损伤是敏感的；根据Ｄ（Ｋ）或Ｄ（Ｃ）与循环次数Ｎ的关系曲线，可以确定材料疲劳损伤的程度并对其疲劳寿命进行估计．     

三轴冲击荷载作用前后软黏土的微观结构变化研究

利用SPAX-2000改进型静动真三轴测试系统进行了软黏土冲击试验,借助扫描电子显微镜观测技术获取了软黏土微观结构图像;提取了孔隙个数、孔隙总面积、面积分级、孔隙总周长、平均孔径、圆度、形状系数和各向异性率共8个微观结构参数;对比了冲击荷载作用前后的微观结构参数变化。研究结果表明,冲击荷载作用下微观结构参数呈现一定的规律变化,该研究成果可为动力排水固结法处理软土地基提供微观理论依据。